1. Field of the Invention
This invention related generally to chlorinators for wastewater treatment systems. More specifically, this invention is a chlorinator for wastewater treatment systems, which have a disinfectant chamber that permits a uniform volume of disinfectant to be used each cycle.
2. Description of the Related Art
Chlorinators, which use either solid or liquid disinfectants, are known to the prior art. Illustrative of chlorinators using solid disinfectants are U.S. Pat. No. 6,183,630 issued to Reeves on Feb. 6, 2001; U.S. Pat. No. 4,100,073 issued to Hopcroft on Jul. 11, 1978; U.S. Pat. No. 5,350,512 issued to Tang on Sep. 27, 1994; and U.S. Pat. No. 5,405,540 issued to Tang on Apr. 11, 1995. Illustrative of chlorinators using liquid disinfectants are U.S. Pat. No. 4,333,833 issued to Longley et. al. on Jun. 8, 1982; U.S. Pat. No. 4,019,983 issued to Mandt on Apr. 26, 1977 and U.S. Pat. No. 3,996,139 issued to Prince et al. on Dec. 7, 1976.
Chlorination is widely used as part of wastewater treatment systems. In practice, a disinfectant such as chlorine is introduced at a point in the wastewater treatment system after which sufficient time, either by flow into a storage tank or through a region of flow, occurs to permit the chlorine to effectively disinfect the contaminant-bearing wastewater. The amount of disinfectant added to the wastewater is referred to as the “dosage,” and is usually expressed as milligrams per liter (mg/l) or parts per million (ppm). The amount of disinfectant necessary to disinfect a particular volume of wastewater is referred to as the “demand.”
The reaction between the disinfectant and the contaminants is typically not instantaneous but is instead time dependent. In order to obtain adequate disinfection, the mixing of wastewater and disinfectant should be completed in the shortest time possible, ideally a fraction of a second. The amount of disinfectant remaining in the wastewater at the time of measurement is referred to as the “residual.” The residual is therefore determined by the demand subtracted from the dosage.
Prior art chlorinators, whether using a liquid or solid disinfectant, typically mix the disinfectant with the wastewater during the flow of wastewater through the wastewater treatment system. In the case of chlorinators using a solid disinfectant, such as those disclosed in U.S. Pat. No. 6,183,630 issued to Reeves on Feb. 6, 2001; U.S. Pat. No. 4,100,073 issued to Hopcroft on Jul. 11, 1978; U.S. Pat. No. 5,350,512 issued to Tang on Sep. 27, 1994; and U.S. Pat. No. 5,405,540 issued to Tang on Apr. 11, 1995, mixing occurs by wastewater flow about a plurality of disinfectant tablets. In such systems the disinfectant is mixed at a rate dependant on the surface area of the table in contact with the wastewater, the density of the wastewater and the flow rate of the wastewater, among other variables. In the case of chlorinators using a liquid disinfectant, such as U.S. Pat. No. 4,333,833 issued to Longley et. al. on Jun. 8, 1982 mixing occurs at a contactor in the flowline wherein disinfectant fluid is drawn from a reservoir by pressure differential. In such systems the amount of chlorine combined with the wastewater varies with the flow rate of the wastewater and; wastewater density. Thus it would be beneficial to the prior art to provide a chlorinator that dispenses a uniform volume of chlorine.
Other chlorinators using liquid disinfectant are likewise known, such as those disclosed in U.S. Pat. No. 6,627,071 issued to Braden on Sep. 30, 2003 and U.S. Pat. No. 6,932,912 issued to Chaffin on Aug. 23, 2005. U.S. Pat. No. 6,627,071 issued to Braden teaches a chlorinator for wastewater treatment systems having a circulation pump and return flow line which includes a disinfectant container, rendered buoyant by a float, floating within a space internal to a tank wherein the buoyant container intakes a determined quantity of disinfectant fluid through a check valve, which terminates communication between the disinfectant container and tank during operation of a circulation pump. After cessation of the circulation pump, the check valve opens to reestablish the quantity of disinfectant fluid. As a result operation is dependent on a functioning check value. U.S. Pat. No. 6,932,912 issued to Chaffin on Aug. 23, 2005 discloses a system which continuously supplies liquid disinfectant so long as the circulation pump is active and the volume of disinfectant can be withdrawn from a single disinfectant reservoir. Such unlimited, as a result of circulation pump action, or unknown, as a result of exhaustion of some unknown volume of disinfectant remaining in the disinfectant reservoir, may result in excessive or inadequate dosage of chlorine. It would therefore be an improvement to properly control the volume of chlorine dispensed.
Typical water treatment systems contain sequential chambers for elimination of solid waste, which would not be consumed by aerobic action, for aerobic treatment of the wastewater, for clarification of the wastewater and for storage of treated wastewater prior to disbursal to the environment by a sprinkler system. Disinfectant is mixed with the treated wastewater between clarification and disbursal. Disbursal of treated wastewater by a sprinkler or line output system is accomplished by mechanical pumping action. Such systems utilize a pump, which generates pressure in excess of that necessary for operation of the attached output system. As a result a pressure relief valve set to the necessary pressure is located in the pump line prior to exit from the pump tank. This valve permits return of a necessary amount of treated wastewater into the pump tank so as not to exceed the necessary output pressure. Return of treated wastewater into the pump tank creates a turbulent area within the treated wastewater in the pump tank.
It would be therefore be an improvement to provide a chlorinator that dispenses a near uniform volume of chlorine into this turbulent area without an external power supply and with no moving parts.